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Movement in and out of cells
Dissolved substances move by diffusion
Active transport:
Substances are absorbed against a concentration gradient
Requires the use of energy from respiration
Cells can absorb ions from a very dilute solution

Other substances such as sugar and ions can also pass through cell membranes.


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The circulation system
The heart pumps blood around the body
Blood flows to the organs through arteries and returns through veins.
In the organs blood flows through capillaries
Substances produced by the cells pass into the blood through the walls of the capillaries
Substances needed by the cells in the…

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The kidneys

A healthy kidney produces urine by:

Filtering the blood

Reabsorbing all the sugar

Reabsorbing the dissolved ions needed
by the body

Reabsorbing as much water as the body

Releasing urea, excess ions and water
as urine

Sugar and dissolved ions may be actively
absorbed against a concentration…

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A donor kidney with the same tissue
type as the recipient

Immunosuppressant drugs- to
suppress the immune system

Dialysis Transplant
Advantages: Advantages:
Readily available Able to have a life
Doesn't require surgery Cheaper
Keeps you alive Keeps you alive
Simpler than transplant Only takes one surgery

Disadvantages: Disadvantages:
Expensive for…

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Micro organisms to make food and drink
Bacteria is used in cheese and yogurt and cheese manufacture
Yeast is used in making bread and alcoholic drinks

Yeast is a single celled organism. The cells have a nucleus, cytoplasm and a membrane surrounded
by a cell wall.

Yeast can respire without…

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Industrial fermenters
Micro organisms can be grown in large vessels called fermenters to produce useful products like
Industrial fermenters usually have:
An air supply to provide oxygen for aerobic respiration
A stirrer to keep the micro organisms in suspension and maintain an even temperature
A water-cooled jacket to remove…

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Using micro organisms safely
Microbes can be grown in a culture medium containing carbohydrates as an energy source, mineral
ions and supplementary protein and vitamins. These nutrients are often contained in an agar
medium which can be poured into a Petri dish.

Petri dishes and the culture medium must be…


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